Connector piece for a fuel pump

ABSTRACT

In the case of a fuel pump, a plug for fixing electric contacts is manufactured from a material which is capable of swelling with fuel, and is inserted into a receptacle of a connecting piece by being fitted therein. Furthermore, the plug and the connecting piece have latching means for simplifying the pre-assembly. The connecting piece requires a particularly low number of components and can be manufactured cost-effectively.

The invention relates to a connecting piece for a fuel pump having areceptacle for a plug with electric contacts for connection of anelectric motor of the fuel pump to an electric network.

Connecting pieces of this type are used in fuel pumps of motor vehiclesnowadays for closing off a common housing of the electric motor and of apump stage, and are known from practice. For installation purposes, theelectric contacts are guided through the sealing lips provided in theconnecting piece and held in place. This makes it possible for the feedpressure produced by the fuel pump to be withstood by the connectingpiece and to be fed to a connector of a supply line. A disadvantage ofthe known connecting piece is that it is complicated to fit. Inaddition, the plastic connecting piece may be damaged duringinstallation of the electric contacts.

Furthermore, a connecting piece has been known from practice, in whichthe plug is encapsulated by the plastic of the connecting piece. Thislikewise requires very complicated manufacturing of the connectingpiece.

The invention is based on the object of designing a connecting piece ofthe type mentioned at the beginning in such a manner that it isparticularly simple to manufacture and to fit.

This object is solved according to the invention by the plug and/or theconnecting piece being manufactured in their/its adjacent regions from amaterial which is capable of swelling with fuel, and by, in the swollenstate, subregions of the plug and of the receptacle bearing directlyagainst one another in a sealing manner.

This design means that the connecting piece according to the inventionrequires neither a sealing ring for sealing the plug nor anencapsulation of the plug in order to seal it relative to adjacentcomponents of the connecting piece according to the invention. Theconnecting piece according to the invention can therefore bemanufactured particularly simply, effectively avoiding damage in theregion of the sealing surfaces.

A contribution is made to the further simplification of themanufacturing of the connecting piece according to the invention if theplug has an encircling edge and is arranged in a recess of thereceptacle with a transition or press fit.

According to another advantageous development of the invention, theinstallation in advance of the plug in the receptacle before swelling ofthe plastic turns out to be particularly simple if the receptacle andthe plug have latching means corresponding with one another. Thelatching means therefore serve as an installation aid for the plug.

Since, when the connecting piece according to the invention is fitted onthe fuel pump, the pressure of the fuel acts on the plug exclusivelyfrom one side, reliable tightness of the plug relative to the receptaclecan be ensured in a simple manner if sealing surfaces of the plug and ofthe receptacle are designed to be substantially planar or funnel-shaped.With a suitable arrangement of the sealing surfaces, the prestress ofthe plug against the receptacle increases with increasing pressurewithin the fuel pump.

The connecting piece known from practice has an inserted metal bearingbushing for the mounting of a shaft of the electric motor of the fuelpump. However, a contribution is made to the further simplification ofthe installation of the connecting piece according to the invention if acup-shaped recess designed as a bearing lug for the direct mounting of ashaft of the electric motor is arranged next to the receptacle. Thismeans that the insertion and fixing of a separately manufactured bearingbushing into the connecting piece according to the invention is nolonger required.

A multiplicity of components can be integrated in the connecting pieceaccording to the invention in a simple manner if two guides for brushesof the electric motor, which brushes are connected to the plug, arearranged next to the receptacle.

The connecting piece according to the invention can be manufacturedparticularly cost-effectively from plastic by injection molding and canbe removed axially from the injection mold in a simple manner if thereceptacle, the guides and the cup-shaped recess are arranged parallelto one another.

According to another advantageous development of the invention,corrosion of connections of electric lines can be reliably avoided ifthe plug has a plastic casing, and if the plastic casing surroundsconnections of the electric contacts to lines leading to the brushes.

Electrostatic charging of the connecting piece according to theinvention can be avoided with a particularly low structural outlay if aground conductor protruding from the plug is guided as far as a loweredge of the connecting piece, which edge is provided for connection to ahousing of the electric motor.

The invention permits numerous embodiments. To further clarify its basicprinciple one of these is illustrated in the drawing and will bedescribed below. In the drawing

FIG. 1 shows, diagrammatically, a fuel pump having a connecting pieceaccording to the invention,

FIG. 2 shows the connecting piece according to the invention from FIG.1, in a subsection,

FIG. 3 shows a greatly enlarged illustration of a detail III of theconnecting piece according to the invention from FIG. 2.

FIG. 1 shows a fuel pump of a motor vehicle with a pump stage 2, whichis driven by an electric motor 1, and with a connecting piece 4, whichis fixed on a housing 3. The connecting piece 4 has a connector 5 for asupply line leading to an internal combustion engine of the motorvehicle. Furthermore, the connecting piece 4 has electric contacts 6 forthe electric motor 1 of the fuel pump.

FIG. 2 shows the connecting piece 4 from FIG. 1 in an enlargedsubsection. The electric contacts 6 are arranged on a plug 7. The plug 7has a plastic casing 8 with inductance coils 9 protruding out of it andwith two brushes 10 for a collector of the electric motor 1 from FIG. 1.The brushes 10 are guided in elongate guides of the connecting piece 4and are prestressed in the direction of the electric motor 1(illustrated in FIG. 1) by means of a spring element. The plug 7 is heldin a receptacle 12 of the connecting piece 4 by latching means 11 and,with an edge 13, penetrates a recess 14 of the connecting piece 4.Furthermore, the connecting piece 4 has, in its center, a cup-shapedrecess 15 for the direct mounting of a shaft of the electric motor 1. Aground conductor 16 is guided from the plug 7 as far as the lower edgeof the connecting piece 4.

FIG. 3 shows the region of the edge 13 of the plug 7 and the recess 14of the connecting piece 4 on a greatly enlarged scale. It can be seenhere that the plastic casing 8 of the plug 7 is directly in contact withthe connecting piece 4. In addition, the edge 13 and the recess 14 aresurrounded by planar sealing surfaces 17, 18 of the plug 7 and of theconnecting piece 4. During feeding of fuel by the fuel pump illustratedin FIG. 1, there is produced within the housing 3 an excess pressurewhich acts on the plug 7 and prestresses the sealing surfaces 17, 18against each other.

The edge 13 of the plug 7 and the connecting piece 4 are manufacturedfrom a plastic which is capable of swelling with fuel, and have atransition fit or a press fit. For installation purposes, the plug 7 isthus introduced into the reception 12 of the connecting piece 4 untilthe latching means 11 hold the plug 7 in its position. In the process,the edge 13 of the plug 7 passes into the recess 14 of the connectingpiece 4. On contact with fuel, edge 13 and the recess 14 swell and thusseal the plug 7 relative to the connecting piece 4.

1. A connecting piece for a fuel pump comprising: a receptacle for aplug, the plug having electric contacts for connection of an electricmotor of the fuel pump to an electric network; wherein the plug or theconnecting piece is capable of swelling with fuel in a region in whichthe plug and the connecting piece are adjacent; and sealing surfaces ofthe plug and the receptacle bear directly against one another in asealing manner in said adjacent region.
 2. The connecting piece asclaimed in claim 1, wherein the plug comprises an encircling edge and isarranged with a transition or press fit in a recess of the receptacle.3. The connecting piece as claimed in claim 1, wherein the receptacleand the plug are engaged in a latching relationship.
 4. The connectingpiece as claimed in claim 1, wherein the sealing surfaces of the plugand of the receptacle are substantially planar or funnel-shaped.
 5. Theconnecting piece as claimed in claim 1, further comprising a cup-shapedrecess arranged next to the receptacle to act as a bearing lug for thedirect mounting of a shaft of the electric motor.
 6. The connectingpiece as claimed in claim 1, further comprising two guides for brushesof the electric motor, wherein the brushes are connected to the plug andare arranged next to the receptacle.
 7. The connecting piece as claimedin claim 10, wherein the receptacle, the guides and the cup-shapedrecess are arranged parallel to one another.
 8. The connecting piece asclaimed claim 6, wherein the plug further comprises a plastic casing tosurround connections of the electric contacts to lines leading to thebrushes.
 9. The connecting piece as claimed in claim 1, wherein the plugfurther comprises a ground conductor protruding therefrom and guided asfar as a lower edge of the connecting piece, which edge is provided forconnection to a housing of the electric motor.
 10. The connecting pieceas claimed in claim 5, further comprising two guides for brushes of theelectric motor, wherein the brushes are connected to the plug and arearranged next to the receptacle.